Hot extrusion of metals

ABSTRACT

A method and apparatus in the hot extrusion of metal billets into solid or tubelike sections in which after extruding the billet into the desired extrudate and an integral discard and prior to removing the extruding ram, the billet container is withdrawn a short distance, but is kept in contact with a portion of the discard.

United States Patent Garin Oct. 2, 1973 HOT EXTRUSION 0F METALS 2,954,869 [0/1960 Swanson 72 272 74 6 [75] Inventor: Jose Ignacio Martinez Garin, Bilbao, 15 3/192 Clark S ain p Primary Examiner-Richard J. Herbst Asslgnee: Cemac, Pans France Assistant ExaminerRobert M. Rogers [22] Filed: y 9 7 Attorney-William H. WC bb Cl. al.

. 21 Appl. No.: 161,075

[57] ABSTRACT 521 US. Cl. 72/255 A method and PP in the extrusion 0f 5 1] Int. Cl. B2lc 23/00 billets sehd mhehke seams in which after [58] Field of Search 72/255, 257, 272 the billet into the desired extrudate and integral discard and prior to removing the extruding ram, [56] References Cited the billet container is withdrawn a short distance, but

UNITED STATES PATENTS is kept in contact with a portion of the discard.

1,479,437 l/l924 Webster 72/272 2 Claims, 4 Drawing Figures PAIENIEDBBI "21m s main;

IN VE N TOR Jose Ignacio Martinez Gar/n BY WMMWWM H/S A TTORNEYS HOT EXTRUSION F METALS My invention relates to the hot extrusion of metal billets into solid and tubelike sections and more particularly to the processing steps which occur after extrusion has taken place and the discard remains in the billet container.

Billets of metals and alloys are hot transformed into solid or tubelike sections in a hot extrusion press which employs a viscous lubricating material. Such a press includes a container for the billet, a die holder, a die, a press platen, and a ram containing a mandrel to form the hollow portion. The ram transfers the force of the press to a dummy block positioned against the billet to force the billet through the die to form the extrudate of the desired size and a discard which remains frictionally engaged in the container. The discard is then severed from the extrudate and removed from the container by ejection against the ram or by an auxiliary jack.

With usual equipment in which the container is continuously maintained coaxial with the press, after the extrusion has taken place and the extrudate is hollow, the mandrel is withdrawn and then the following sequence of operations occur: (1) withdrawing the ram, (2) withdrawing the container integral with the discard and the extrudate, (3) sawing the extrudate ahead of the discard and (4) continuing the withdrawal of the container, which causes the discard to be ejected by bumping against the ram.

On certain presses where one or several containers are capable of transverse travel, the above first three operations are carried out and then the container is transversely moved to an off center station where the discard is ejected by means of an auxiliary jack.

The ejection of the discard requires considerable effort and a substantial shock is placed on the equipment with each ejection. Specifically, the cylindrical container wall in the vicinity of the die shows appreciable wear resulting from the impact necessary for ejection and, of course, such wear is detrimental to the proper alignment of the press.

Further, the existing placement of the jacks which insures the successive withdrawals of the container must have, at the same time, a sufficient stroke for retracting the container to its rearward position, as well as sufficient force for causing the discard to be ejected by the ram. A substantial waste of energy occurs in this process and the increase in temperature and wear of the hydraulic circuits is appreciable.

My invention avoids these various problems of wear and tear on the equipment by making the ejection of the discard easier. The particular method of making the discard ejection easier is accomplished through a minimum amount of force which is noticeably smaller than the forces exerted by the known practices.

My invention is a method and apparatus for the hot extrusion of metal billets into solid and tubelike sections in which after the extrudate is formed and is still integral with the discard, the container is slightly withdrawn without moving the ram or the discard so as to minimize the force ultimately necessary for ejection, and then proceeding with the withdrawal of the ram and the known subsequent steps.

In the accompanying drawings, I have shown one preferred embodiment of my invention in which:

FIG. 1 represents the prior art extrusion process immediately after extrusion has taken place;

FIG. 2 represents the prior art extrusion operation when the extrudate is being severed from the discard;

FIG. 3 represents my invention after extrusion wherein the container has been slightly withdrawn from the die holder and discard; and

FIG. 4 represents my invention at the time the extrudate is being severed from the discard.

FIG. 1 represents the portion of the extrusion press involved in my improved method of operation. Specifically, a hot billet is placed into container 1 and the force of the press exerted thereto through ram 5 and a dummy block 6 therebetween to force the billet through the die insert 3 held by the die holder 2 to form an extrudate 7 of the desired configuration and a nondeformed portion of the billet known as the discard 8. The hollow section is made by a mandrel 4 which is retractable into the ram 5.

The representation of FIG. 1 shows the extrusion process just after the extrusion has taken place and the mandrel 4 has been removed. In accordance with known practices, the ram 5 is withdrawn and then the container 1, together with the dummy block 6, the discard, the extrudate 7 and in the case of FIG. I, the die insert 3 is withdrawn. Movement of the cylinder 1 includes movement of the discard 8 since the discard 8 is bound or stuck to the container 1 as a result of the compression of the billet within the container 1 effected during the extrusion operation. After the container 1 is withdrawn, FIG. 2, a separating device such as circular saw 9 severs the extrudate 7 from the discard 8 and then the container 1 is further withdrawn until the discard 8 is ejected by the now stationary ram 5 or by an auxiliary jack in the case where the container is transversely moved to another station. Where a second station is employed, the ram 5 must be completely removed to permit transfer of the container 1.

I have found that a slight withdrawal of the container before any withdrawal of the ram substantially reduces the force required for the ejection of the discard. If, however, the first withdrawal of the container in accordance with my invention is too long in terms of distance, the container would no longer be in sufficient contact with the discard to remove the discard and the extrudate in the subsequent steps to permit their separation.

My invention is best explained by reference to FIGS.

7 3 and 4. The ram 5 is left stationary after the extrusion has taken place and the container 1 is withdrawn a short distance (I). Discard 8 remains stationary against dummy block 6 and ram 5 so only container 1 moves. The contact area between the container 1 and the discard 8 is, therefore, less than that depicted in FIG. 1 for the prior art. The processing sequence then can continue in a known manner with the known long stroke jacks. The ram 5 is then withdrawn, followed by the container 1, together with the dummy block, discard 8, extrudate 7, and in the case of FIG. 3, the die insert 3. The saw 9 then separates the extrudate 7 from the discard 8 and the container is further withdrawn to eject the discard by means of the ram 5 or by means of an auxiliary jack in the situation when the container is moved to another station. As will be shown by specific example, the force required to finally eject the discard is substantially less than that required heretofore.

I have found that for most standard Presses the distance (I) that is, the distance of withdrawal of the container I from the die holder 2 should be about 2 to 20 The force necessary for unsticking the discard in the first withdrawal of the container 1 in accordance with my invention, is advantageously supplied by a set of at least two jacks l and 11 which are symmetrically placed about the central axis of the press and housed in the downstream platen (not shown) of the press. These jacks which are of the standard type have a use- 'ful stroke of 2 to 20 mm. The jacks and 11 are positioned so as to rest against the downstream face of the container 1 when the container 1 is in its closed forward position. By placing the jacks l0 and 11 in this manner and following the steps of my invention, the ejection takes place through a force which is noticeably smaller than in the known practice.

The following example is exemplary of the advantages to be gained by my invention. A horizontal hydraulic 3000 ton press included two containers assembled on a turret with a horizontal axis. The turret was capable of occupying in turn a position coaxial with the press for the extrusion operation itself and an off centered position for various auxiliary operations such as ejecting the discard.

According to the known practice, this press was equipped with two jacks having a total force of 100 tons and a stroke of 100 mm (4 inches) to separate the container from the die holder after the ram had fully been withdrawn so that the discard could travel integral with the container. .lacks with a total force of 28 tons ensured the final withdrawal of the container carrying turret along 300 mm (12 inches). The ejection of the discard at the off centered position required a force sometimes exceeding 450 tons with a 100 mm (4 inches) stroke. The ejection of the discard resulted in repeated impact and vibrations in the mass of the container carrying turret and a noticeable wear of the container liner.

By following my invention, two jacks positioned in the press platen and having a total force of 500 tons with only a 15 mm (0.6 inch) stroke, ensured in one operation both the separation between the container and die holder and the unsticking of the discard, which was kept motionless by the ram. The withdrawal of the container carrying turret had not been altered. The ejection of the discard at the off centered position required a force smaller than 200 tons with a mm (4 inches) stroke. The ejection of the discard was conducted without any appreciable impact vibrations or wear of the liner.

In view of the strokes along which the forces are applied when following my invention, the involved hydraulic energy has dropped from 63.4 to 35.9 meter tons (460,000 to 260,000 ft.]lb.). This has eliminated any serious increase in the temperature of the hydraulic circuits and has avoided the corresponding waste of energy.

I claim:

1. In the hot extrusion of metal billets into solid and tubelike sections in a hot extrusion press by the sequential steps of extruding the billet from a container through a die adjacent thereto by means of a force transmitting ram into the desired section having an integral discard remaining in the container, removing the ram, withdrawing the container and thus the discard and section, said discard being in contact with said container and sticking thereto, severing the section forward of the discard and ejecting the discard, the improvement comprising after extruding and prior to removing the ram, withdrawing the container a very short distance without withdrawing the ram and the discard, said discard still having contact with said container.

2. The improvement of claim 1 wherein the container is withdrawn at distance of between 2 and 20 mm.

UNl'lED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3, Z03 Dated October 1973 I flfi) Jose Ignacio Martinez Garin It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

After the line listing the application serial number insert the following:

--Foreign Application Priority Data July 15, 1970 France 70/25. 935--.

Signed and sealed this 29th day of January 197E.

( SEAL) Att e st 2 EDWARD M, FLETCHER, JRQ RENE D. TEGTMIEYER Attesting Officer Acting Commissioner of Patents ORM P0405) (10-69) I USCOMM-DC 60376-P69 U.S. GOVERNMENT PRINTING OFFICE I969 0-366-33L 

1. In the hot extrusion of metal billets into solid and tubelike sections in a hot extrusion press by the sequential steps of extruding the billet from a container through a die adjacent thereto by means of a force transmitting ram into the desired section having an integral discard remaining in the container, removing the ram, withdrawing the container and thus the discard and section, said discard being in contact with said container and sticking thereto, severing the section forward of the discard and ejecting the discard, the improvement comprising after extruding and prior to removing the ram, withdrawing the container a very short distance without withdrawing the ram and the discard, said discard still having contact with said container.
 2. The improvement of claim 1 wherein the container is withdrawn a distance of between 2 and 20 mm. 